Influence of Pressure on the Intramolecular Spin Exchange in a Short Imidazolium-Nitroxide Biradical |
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| Authors: | Boryana?Mladenova-Kattnig Günter?Grampp Email author" target="_blank">Alexander?I?KokorinEmail author |
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| Institution: | 1.Institute of Physical and Theoretical Chemistry,Graz University of Technology,Graz,Austria;2.N. N. Semenov Institute of Chemical Physics,Russian Academy of Sciences,Moscow,Russian Federation |
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| Abstract: | A short-chain imidazoline-type nitroxide biradical R 5 NO –CH=N–N=C(CH3)–R 5 N , B2, with nitroxide rings R 5 N and R 5 NO as 1-oxyl-2,2,5,5-tetramethyl-3-imidazoline and 1-oxyl-2,2,5,5-tetramethyl-3-N-oxide imidazoline, respectively, has been studied using X-band electron paramagnetic resonance (EPR) spectroscopy in CH3CN solutions at variable temperature T and pressure P. Changes of the solution viscosity on the intramolecular electron spin exchange in B2 is characterized by calculating the value of the exchange integral |J/a|, where a denotes the 14N hyperfine splitting (hfs) constant. It is revealed that the intramolecular dynamics in B2 do not follow the Debye–Stokes–Einstein law, while the Arrhenius dependence is fulfilled. Probable reasons of such behavior are discussed. |
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